How far does space go?

A:

From Earth's surface, outer space begins at the somewhat-arbitrary Karman Line, or 100 km up, according to the Space website. From there, the observable universe stretches out without reaching any perceptible boundary.

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As of 2014, the universe is 13.8 billion years old, Space reports. Given the speed of light, this places the farthest objects that can be seen from Earth as those that sit on that boundary. The universe is expanding, so objects at the extreme range of detection have since moved to a maximum distance of 48 billion light-years. Space goes on beyond that. If the universe has a flat curvature, which it very likely does, then space could be said to extend, literally, forever.

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In 2009, scientists at the University of Calgary used measurements of atmospheric wind and the flow of charged particles to determine that space begins at 73 miles above the Earth's surface. However, there are competing, and sometimes conflicting, assessments of Earth's boundaries.

According to the National Aeronautics and Space Administration, astronauts are sent into space to operate the International Space Station, help develop commercial spaceflight, investigate the possibilities of human exploration of deep space, develop new technologies and conduct research in a wide range of scientific fields. Many aspects of scientific studies of the Earth and the rest of the universe are easier to conduct from space.

As of 2013, the National Aeronautics and Space Administration determined, with a margin of error of only 0.4 percent, that the universe is infinite in size. The observable universe extends 92 billion light years in diameter. The exact size of the universe, or if there are multiples, is unknown.

The no boundary theory of the universe likens the universe to the Earth, in that is impossible to find any boundaries traveling around the Earth or to fall off it. This is possible as a result of theorizing that prior to the Big Bang, the generally accepted laws of physics did not apply and that the concept of time as we know it did not exist.